Browsing by Author "Logan, Timothy"

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Collaborative Research: Contrasting the Effects of Aerosols on MBL Cloud-precipitation Properties and Processes in Boreal and Austral Mid-latitude Regions
Atmospheric Sciences; TAMU; https://hdl.handle.net/20.500.14641/243; National Science Foundation
The project is to investigate formation of marine-boundary-layer clouds, which are clouds that are directly influenced by the ocean. Particularly, how tiny suspended particles or aerosols contribute to clouds and how clouds interact with aerosols. Aerosols are generated from atmospheric, land, and oceanic processes such as urban/industrial activity, dust storms, burning vegetation, biological activity, sea spray, wind currents, and volcanoes. Certain aerosol types can initiate marine-boundary-layer cloud development more easily than others. This adds to the complexity and uncertainty of marine-boundary-layer cloud impacts on weather variations. Marine-boundary-layer clouds have significant climatological effects on the hydrological cycle and the Earth?s radiation balance. For example, varying distributions of marine-boundary-layer clouds around the globe contribute to areas of deficits and surpluses in solar energy and rainfall. Many studies have been conducted on aerosol-cloud interactions in the Northern Hemisphere where most of the global population and landmasses are located. Not much is known over the vast area of remote land and oceanic regions in the Southern Hemisphere. This study will investigate differences and similarities of aerosol-cloud interactions between the Northern and Southern Hemispheres by analyzing recent field observations and utilizing numerical model simulations. The project involves undergraduate and graduate students to participate in the research project and train them to be the next generation of scientists. This study employs long-term ground-based observations and remote sensing retrievals from a dedicated observation site in the Eastern North Atlantic Ocean and aircraft in situ measurements from two intensive field campaigns in 2018: 1) the Aerosol and Cloud Experiments in the Eastern North Atlantic (ACE-ENA), and 2) the Southern Ocean Clouds, Radiation, Aerosol Transport Experimental Study (SOCRATES). The research team utilizes a synergistic measurement/modeling approach in conjunction with meteorological patterns to compare the characteristics of marine-boundary-layer aerosol, cloud, and drizzle properties over the two hemispheres through answering three scientific questions. Those are: 1) what are the relative roles of surface cloud condensation nuclei and updrafts in aerosol-cloud interactions over the marine boundary layer and warm rain processes? 2) what are the characteristics of marine-boundary-layer aerosol, cloud and drizzle properties and their interactions during two field campaigns? 3) what are the characteristics of marine-boundary-layer aerosol, cloud, and drizzle properties, their interactions over the Southern Ocean, and their similarities and differences compared with those in the Eastern North Atlantic Ocean? Comparisons of precipitation processes and aerosol-cloud interactions at the two sites with significantly different environmental conditions will shed light on the controlling factors in aerosol-cloud interactions and eventually lead to a generalized parameterization for aerosol-cloud interactions applicable for the global climate models. This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.
Collaborative Research: Contrasting the Effects of Aerosols on MBL Cloud-precipitation Properties and Processes in Boreal and Austral Mid-latitude Regions
Atmospheric Sciences; TAMU; https://hdl.handle.net/20.500.14641/243; National Science Foundation
The project is to investigate formation of marine-boundary-layer clouds, which are clouds that are directly influenced by the ocean. Particularly, how tiny suspended particles or aerosols contribute to clouds and how clouds interact with aerosols. Aerosols are generated from atmospheric, land, and oceanic processes such as urban/industrial activity, dust storms, burning vegetation, biological activity, sea spray, wind currents, and volcanoes. Certain aerosol types can initiate marine-boundary-layer cloud development more easily than others. This adds to the complexity and uncertainty of marine-boundary-layer cloud impacts on weather variations. Marine-boundary-layer clouds have significant climatological effects on the hydrological cycle and the Earth?s radiation balance. For example, varying distributions of marine-boundary-layer clouds around the globe contribute to areas of deficits and surpluses in solar energy and rainfall. Many studies have been conducted on aerosol-cloud interactions in the Northern Hemisphere where most of the global population and landmasses are located. Not much is known over the vast area of remote land and oceanic regions in the Southern Hemisphere. This study will investigate differences and similarities of aerosol-cloud interactions between the Northern and Southern Hemispheres by analyzing recent field observations and utilizing numerical model simulations. The project involves undergraduate and graduate students to participate in the research project and train them to be the next generation of scientists. This study employs long-term ground-based observations and remote sensing retrievals from a dedicated observation site in the Eastern North Atlantic Ocean and aircraft in situ measurements from two intensive field campaigns in 2018: 1) the Aerosol and Cloud Experiments in the Eastern North Atlantic (ACE-ENA), and 2) the Southern Ocean Clouds, Radiation, Aerosol Transport Experimental Study (SOCRATES). The research team utilizes a synergistic measurement/modeling approach in conjunction with meteorological patterns to compare the characteristics of marine-boundary-layer aerosol, cloud, and drizzle properties over the two hemispheres through answering three scientific questions. Those are: 1) what are the relative roles of surface cloud condensation nuclei and updrafts in aerosol-cloud interactions over the marine boundary layer and warm rain processes? 2) what are the characteristics of marine-boundary-layer aerosol, cloud and drizzle properties and their interactions during two field campaigns? 3) what are the characteristics of marine-boundary-layer aerosol, cloud, and drizzle properties, their interactions over the Southern Ocean, and their similarities and differences compared with those in the Eastern North Atlantic Ocean? Comparisons of precipitation processes and aerosol-cloud interactions at the two sites with significantly different environmental conditions will shed light on the controlling factors in aerosol-cloud interactions and eventually lead to a generalized parameterization for aerosol-cloud interactions applicable for the global climate models.
Collaborative Research: Evaluating the Influences of Aerosols on Low-level Cloud-precipitation Properties over Land and Ocean Using Long-term Ground-based-Observations and WRF Simulations
Atmospheric Sciences; TAMU; https://hdl.handle.net/20.500.14641/243; National Science Foundation
Aerosol generation resulting from natural and anthropogenic activities is expected to have considerable, far-reaching effects on cloud development and the hydrologic cycle. Though the aerosol direct effect can simply be thought of as a reduction of incoming solar radiation reaching the Earth's surface, the aerosol indirect effect (AIE) involves a complex set of aerosol-cloud-precipitation interactions. These indirect effects include the alteration of cloud microphysical properties such as cloud lifetime, droplet size distribution, liquid water content and path, optical depth, and albedo. Precipitation processes will certainly be affected in numerous and at times, detrimental ways. Hence, there is a major impact to society as a whole due to a heavy dependence on the distribution of available water over a given region for public consumption, agriculture, and industrial purposes. Intellectual Merit: This research adopts a synergistic approach that uses the long-term ground-based observations and retrievals from the Southern Great Plains of the United States and Eastern North Atlantic Ocean regions to investigate the seasonal and diurnal variations of aerosol and clouds under the continental and maritime conditions, as well as compare their similarities and differences. Air parcel trajectory modeling will be conducted to identify the sources of air masses for the selected cases to investigate the AIEs over these two regions with additional WRF simulations. This study is important because it will aid to improve aerosol and cloud parameterizations as well as provide an in-depth understanding of aerosol-cloud-precipitation interactions in typical maritime and continental conditions. The following three scientific questions (SQs) will be investigated. SQ1: What are the similarities and differences of aerosol-cloud properties, as well as their interactions over ocean and land? SQ2: What are the indirect effects of aerosols on cloud microphysical properties? SQ3: How does wind shear enhance turbulent mixing and stimulate drizzle formation? Broader Impacts: This research will benefit society by helping to provide better support for the modeling of aerosol-cloud-precipitation interactions which will aid in researching the long-term distribution of available water by clouds and precipitation processes. The far-reaching goal of this project is to further reduce uncertainties in the climate modeling community by providing better constraints for seasonal and regional aerosol and cloud properties. Moreover, there will be plenty of opportunities to introduce aerosol-cloud interactions as "real world" examples in undergraduate and graduate geoscience courses where the students can not only investigate these examples as interdisciplinary class projects, but also improve upon current research techniques and develop their own theses and dissertation areas of focus.